Originally Published MPMN March 2002

SPECIAL

Low-power microchip brings music to users' ears, rhythm to ailing hearts

A mixed-signal microchip designed to minimize power loss may be the missing component needed to make smaller hearing aids and pacemakers with extended battery lives. Codesigned by Zarlink Semiconductor (San Diego; www.zarlink.com) and Cochlear Ltd. (Sydney, Australia; www.cochlear.com), the Babel 24 microchip is constructed in a special complementary metal-oxide semiconductor (CMOS) technology that is configured for power efficiency rather than speed. "About 90% of CMOS devices on the market are configured for speed, which is required for many applications but also demands a lot of power," says Zarlink director of medical product marketing François Pelletier. "Our chip is designed with low-leak transistors and special drain techniques for the remaining 10% of applications in which extending battery life is more important."

The Esprit 3G hearing aid is one of the first products to benefit from this novel technology. Marketed by Cochlear, the low power requirement for this device enabled all external components to be condensed into a single speech-processor box that is small enough to wear behind the ear, making it the world's first behind-the-ear speech processor for people with severe hearing impairments. "The Babel 24 microchip used in this device draws less than 2 mA at 3.7 V," says Pelletier. "That's about one-tenth the power requirement of other products on the market." Pelletier estimates that the chip extends the unit's battery life to 2 weeks. Despite low power requirements, however, the chip remains powerful enough to process signals from the aid's internal telecoil and plug-in FM receiver in addition to performing standard functions.

Pacemakers also stand to benefit significantly from this technology due to the difficulties incurred during battery replacement. "Speed is not really a concern for pacemakers, which run in frequencies of megahertz rather than kilohertz," says Pelletier. "Instead, it's more important that the batteries last as long as possible since replacement is impractical." The Zarlink and Cochlear pacemaker chip draws 5 mA at 3 V, allowing unit batteries to last for up to 8 years.

But pacemakers and hearing aids are not the only devices that can use this technology. "Right now we're developing these chips for brain stimulators, bladder control devices, and even a swallowable camera," notes Pelletier.

Benjamin Lichtman, Norbert Sparrow, Katherine Sweeny, Zachary Turke, and Susan Wallace

Copyright ©2002 Medical Product Manufacturing News